Apparatus for controlling water pump of hybrid vehicle and method thereof

ABSTRACT

A water pump control apparatus and method of a hybrid vehicle are used to control a motorized water pump according to the heat emission amount of an engine. The apparatus and method include calculating a temperature difference by detecting a temperature of a coolant exhausted from an engine and a temperature of the coolant flowing to an engine, calculating a heat emission amount of the engine by applying a circulating coolant flux to the temperature difference, and driving a motorized water pump with a driving power in proportion to the heat emission amount of the engine.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to and the benefit of Korean Patent Application No. 10-2010-0040329 filed in the Korean Intellectual Property Office on Apr. 29, 2010, the entire contents of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

(a) Field of the Invention

The present invention relates to a water pump control apparatus of a hybrid vehicle. More particularly, it relates to a water pump control apparatus that controls a motorized water pump according to a heat emission amount of an engine, and a control method thereof.

(b) Description of the Related Art

Hybrid vehicles have been developed and mass produced in a manner that satisfies exhaust gas regulations and enhances fuel efficiency.

There are a variety of types of hybrid vehicles, and while an engine and a motor are generally applied as a power source, there are both EVs (electric vehicles) that are driven by only a motor, and HEVs (hybrid electric vehicles) that are driven by an engine and a motor.

In hybrid vehicles, a coolant is forcibly circulated so as to prevent overheating of the engine, a coolant passage is formed respectively in a cylinder block and a cylinder head of the engine, and a water pump circulates the coolant through the coolant passage so as to cool the engine.

Accordingly, fuel efficiency and exhaust gases can be stabilized in a condition that the engine is warmed up. However, as the warming period of the engine becomes longer, the fuel efficiency may suffer and the exhaust gas quality is deteriorated.

The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.

SUMMARY OF THE INVENTION

In one aspect, according to the present invention, a water pump control apparatus of a hybrid vehicle is provided that is capable of optimizing cooling efficiency by controlling the motorized water pump according to the heat emission amount of the engine.

A water pump control apparatus of a hybrid vehicle according to an exemplary embodiment of the present invention preferably includes at least a thermostat configured to determine a circulation direction of a coolant according to a temperature of the coolant that is exhausted from an engine, a motorized water pump mounted between the engine and the thermostat for circulating the coolant, a first coolant temperature sensor configured to detect the temperature of the coolant flowing from the engine to a cooler, a second coolant temperature sensor configured to detect a temperature of the coolant flowing from the cooler to the engine, and a control portion that applies a temperature difference detected by the first and second coolant temperature sensors and a coolant flux to calculate a heat emission amount of the engine, and thus drive the motorized water pump according to the heat emission amount.

The control portion may output a warning signal and simultaneously enter into a limp home mode so as to continuously drive the motorized water pump with a predetermined driving power such that the coolant continuously circulates, if it is determined that the cooling system is in an abnormal condition.

The control portion may determine driving power and drive the motorized water pump in proportion to the heat emission amount of the engine by calculating a compensation factor according to the coolant temperature and applying the compensation factor to the driving power so as to drive the motorized water pump more rapidly in a condition in which the coolant temperature is rising.

A water pump control method of a hybrid vehicle according to an exemplary embodiment of the present invention may include calculating a temperature difference by detecting the temperature of a coolant exhausted from an engine and the temperature of the coolant flowing to an engine, calculating a heat emission amount of the engine by applying a circulating coolant flux to the temperature difference, and driving a motorized water pump with a driving power in proportion to the heat emission amount of the engine.

The water pump control method may further include driving the motorized water pump with driving power in proportion to the heat emission amount if the coolant temperature is steady, and calculating a compensation factor according to the coolant temperature, applying the compensation factor to the driving power, and calculating final driving power so as to drive the motorized water pump more rapidly if the heat emission amount and the coolant temperature are raised.

The present invention as stated above preferably drives the motorized water pump in proportion to the heat emission amount of the hybrid vehicle engine to optimally circulate the coolant such that hot spots of the engine are reduced, stability thereof is improved, and engine efficiency is improved by optimized cooling.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of a water pump control apparatus of a hybrid vehicle according to an exemplary embodiment of the present invention.

FIG. 2 is a flowchart depicting a water pump control process of a hybrid vehicle according to an exemplary embodiment of the present invention.

FIG. 3 is a graph showing water pump control timing of a hybrid vehicle according to an exemplary embodiment of the present invention.

DESCRIPTION OF SYMBOLS

100: engine

110: first coolant temperature sensor

120: the second temperature sensor

130: radiator

140: thermostat

150: motorized water pump

160: control portion

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Hereinafter, in the following detailed description, only certain exemplary embodiments of the present invention have been shown and described, simply by way of illustration.

As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention, and the drawings and description are to be regarded as illustrative in nature and not restrictive.

It is understood that the term “vehicle” or “vehicular” or other similar term as used herein is inclusive of motor vehicles in general such as passenger automobiles including sports utility vehicles (SUV), buses, trucks, various commercial vehicles, watercraft including a variety of boats and ships, aircraft, and the like, and includes hybrid vehicles, electric vehicles, plug-in hybrid electric vehicles, hydrogen-powered vehicles and other alternative fuel vehicles (e.g. fuels derived from resources other than petroleum). As referred to herein, a hybrid vehicle is a vehicle that has two or more sources of power, for example both gasoline-powered and electric-powered vehicles.

FIG. 1 is a schematic diagram of a water pump control apparatus of a hybrid vehicle according to an exemplary embodiment of the present invention.

As shown in FIG. 1, the present invention preferably includes an engine 100 as a power source, a first coolant temperature sensor 110, a second coolant temperature sensor 120, a radiator 130, a thermostat 140, a motorized water pump 150, and a control portion 150.

The first coolant temperature sensor 110 detects a temperature of a coolant circulating from the engine 100 to the radiator (cooler) 130 and transfers the detected signal to the control portion 160.

The second coolant temperature sensor 120 detects a temperature of the coolant circulating from the radiator (cooler) 130 or a bypass line to the engine 100 and transfers the detected signal to the control portion 160.

The core of the radiator 130 preferably has a wide contact surface with air to effectively radiate heat absorbed in the coolant, and a cooling fan (not shown) is set to forcibly blow air through the core so as to improve the radiating efficiency according to the coolant temperature and the driving conditions of the vehicle.

The thermostat 140 is configured to change the circulation direction of the coolant exhausted from the engine 100 to the bypass line or the radiator 130 according to the coolant temperature.

The motorized water pump 150 preferably is disposed between the engine 100 and the thermostat 140, where the control portion 160 turns the motorized water pump 150 off or on or varies a driving power for driving the motorized water pump 150 so as to vary the coolant flow amount. The motorized water pump 150 can be one of a clutch-type water pump and an electrical water pump.

The control portion 160 calculates a heat emission amount as a cooling demand according to driving of the engine 100, and controls driving power for driving the motorized water pump 150 in proportion to the heat emission amount.

The control portion 160 detects the coolant temperature of the coolant flowing from the engine 100 to the cooler through the first coolant temperature sensor 110, detects the coolant temperature of the coolant flowing from the cooler to the engine 100 through the second coolant temperature sensor 120, calculates the temperature difference between them, and multiplies the temperature difference by the coolant flow amount (flux) circulating between the engine 100 and the cooler to calculate the heat emission amount of the engine 100, for example, according to the following formula:

Q (heat emission amount)=m (flux)×c (specific heat)×ΔT (temperature difference)

The heat emission amount of the engine 100 can be determined by utilizing experimental data according to car models, and can be expressed as two-dimensional map data.

The control portion 160 is configured to analyze driving conditions and environmental conditions such as outside temperature, engine speed, and an ISG (idle stop and go) state, and if it is determined that the cooling system is in error, the control portion 160 outputs an alarm signal and simultaneously enters is into a limp home mode such that the motorized water pump 150 can be continuously operated.

In a case that the heat emission amount of the engine 100 is sharply increased, the control portion 160 increases the driving power for driving the motorized water pump 150 so as to decrease a hot spot of the engine 100, because the engine 100 can be vulnerable at a high temperature compared to a low temperature.

For instance, if the heat emission amount is increased in a condition that the coolant temperature is steady, the control portion 160 drives the motorized water pump 150 in proportion to the heat emission amount, and if the heat emission amount and the coolant temperature are increased, the control portion 160 determines a driving power in proportion to the heat emission amount, multiples a compensation factor by the driving power to calculate final driving power, and drives the motorized water pump 150 with the final driving power.

Operation of a water pump control apparatus according to the present invention including the functions described above will hereinafter be described in detail with reference to FIG. 2, which is a flowchart that depicts a water pump control process according to an exemplary embodiment of the present invention.

The control portion 160 can diagnose driving conditions and environmental conditions from sensors in a hybrid vehicle in step 5101, diagnose a cooling system in step S102, and determine whether the cooling system is in a normal condition or not in step S103.

If it is determined that the cooling system is in an abnormal condition in step S103, the control portion 160 outputs an alarm signal in a predetermined form, enters into a limp home mode in step S113, and drives the motorized water pump 150 with a predetermined driving amount so as to continuously circulate the coolant in step S114.

Meanwhile, if it is determined that the cooling system is in a normal condition in step S103, the control portion 160 detects the temperature of the coolant circulating from the engine 100 to the cooler through the first coolant temperature sensor 110 and detects the temperature of the coolant circulating from the cooler to the engine 100 through the second coolant temperature sensor 110, and calculates a temperature difference between them in step S104.

The control portion 160 multiplies the temperature difference by the coolant flowing amount (flux) circulating between the engine 100 and the cooler to calculate the heat emission amount of the engine 100 in step 105.

It is determined whether the heat emission amount of the engine 100 exceeds a predetermined value necessary to circulate the coolant in step S106.

If the heat emission amount of the engine 100 is less than the predetermined value in S106, the control portion 160 stops operation of the motorized water pump 150 so as to not circulate the coolant in the S107.

However, if it is determined that the heat emission amount of the engine 100 is greater than the predetermined value in the S106, the control portion 160 determines a driving power that is proportional to the heat emission amount of the engine 100 and drives the motorized water pump 150 with the driving power such that the coolant effectively cools the engine in step S109.

While the control portion drives the motorized water pump 150 in proportion to the heat emission amount of the engine 100, the heat emission amount of the engine 100 and the coolant temperature are raised and it is determined whether the coolant temperature detected from the first coolant temperature sensor 110 exceeds a predetermined temperature (A° C.) in step S110.

The predetermined temperature (A° C.) can be changed according to an operating load, and is generally set as a value ranging from about 85° C. to about 95° C.

If the coolant temperature does not exceed the predetermined temperature (A° C.) in step S110, it is returned to step S108 and the motorized water pump 150 is driven with driving power that is proportional to the heat emission amount.

However, if the coolant temperature exceeds the predetermined temperature (A° C.) in step S110, the control portion determines a driving power that is proportional to the heat emission amount of the engine 100, applies a coefficient factor according to the coolant temperature to the driving power to extract the final driving power in step S111, and the control portion 160 drives the motorized water pump 150 with the final driving power so as to quickly circulate the coolant.

FIG. 3 is a graph showing a water pump control timing of a hybrid vehicle according to an exemplary embodiment of the present invention. As shown in FIG. 3, the motorized water pump is driven in proportion to the heat emission amount of the engine in a section where the coolant temperature is steady, if the heat emission amount and the coolant temperature continuously rise, the coefficient factor according to the heat emission amount and the coolant temperature is applied to drive the motorized water pump at a higher load.

Accordingly, the coolant can circulate corresponding to the cooling demand of the engine such that the hot spot inside the engine is decreased and the engine is not overcooled to improve the efficiency thereof.

While this invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims, 

1. A water pump control apparatus of a hybrid vehicle, comprising: a thermostat configured to determine a circulation direction of a coolant according to a temperature of the coolant that is exhausted from an engine; a motorized water pump mounted between the engine and the thermostat for circulating the coolant; a first coolant temperature sensor configured to detect the temperature of the coolant flowing from the engine to a cooler; a second coolant temperature sensor configured to detect a temperature of the coolant flowing from the cooler to the engine; and a control portion that applies a temperature difference detected by the first and second coolant temperature sensors and a coolant flux to calculate a heat emission amount of the engine, the control portion configured to drive the motorized water pump according to the heat emission amount.
 2. The water pump control apparatus of claim 1, wherein the control portion outputs a warning signal and simultaneously enters into a limp home mode so as to continuously drive the motorized water pump with a predetermined driving power such that the coolant continuously circulates, if it is determined that the cooling system is in an abnormal condition.
 3. The water pump control apparatus of claim 1, wherein the control portion drives the motorized water pump in proportion to the heat emission amount of the engine, and the control portion determines driving power in proportion to the heat emission amount of the engine, calculates a compensation factor according to the coolant temperature, and applies the compensation factor to the driving power so as to drive the motorized water pump more rapidly in a condition in which the coolant temperature is rising.
 4. A water pump control method of a hybrid vehicle, comprising: calculating a temperature difference by detecting a temperature of a coolant exhausted from an engine, and a temperature of the coolant flowing to an engine; calculating a heat emission amount of the engine by applying a circulating coolant flux to the temperature difference; and driving a motorized water pump with a driving power in proportion to the heat emission amount of the engine.
 5. The water pump control method of claim 4, further comprising: driving the motorized water pump with the driving power in proportion to the heat emission amount if the coolant temperature is steady; calculating a compensation factor according to the coolant temperature; applying the compensation factor to the driving power; and calculating a final driving power so as to drive the motorized water pump more rapidly if the heat emission amount and the coolant temperature are raised. 